How to Use Prepared Statements with MySQL in Python?

Using Prepared Statements with MySQL in Python: A Detailed Explanation

Understanding the Syntax

Prepared statements in MySQL offer a more efficient and secure way to execute queries by separating the query preparation phase from the execution phase. When using prepared statements, it's important to follow the correct syntax to avoid potential errors.

Error Explanation

In your code snippet, you encounter an error because you are using the incorrect syntax for prepared statements. Here's a breakdown of the issue:

sql = "PREPARE stmt FROM ' INSERT INTO {} (date, time, tag, power) VALUES (?, ?, ?, ?)'".format(self.db_scan_table)
self.cursor.execute(sql)

This line attempts to prepare a statement named "stmt" using a SQL string. However, Python's MySQLdb module doesn't support the "PREPARE" and "EXECUTE" commands directly.

Solution Using MySQLdb

To use prepared statements with MySQLdb, you need to use a slightly different approach:

sql = ('INSERT INTO {} (date, time, tag, power) VALUES (%s, %s, %s, %s)'.format(self.db_scan_table))

This line creates a SQL string with placeholders ("?" characters) for the values to be inserted.

self.cursor.execute(sql, (d, t, tag, power))

This line executes the prepared statement using the specified values in the tuple. MySQLdb automatically prepares the statement and handles the execution.

Using MySQL Connector/Python

A more modern and efficient way to use prepared statements with MySQL in Python is to use MySQL Connector/Python. It offers an explicit "prepare=True" option in the cursor factory:

cursor = conn.cursor(prepared=True)

sql = ('INSERT INTO {} (date, time, tag, power) VALUES (%s, %s, %s, %s)'.format(self.db_scan_table))

cursor.execute(sql, (d, t, tag, power))

This approach provides greater control over prepared statements and is recommended for improved performance and security.

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